Using SIP for Ubiquitous and Location-Based Communications Henning Schulzrinne (with Stefan Berger, Jonathan Lennox, Maria Papadopouli, Stelios Sidiroglou, Kundan Singh, Xiaotao Wu, Weibin Zhao) Columbia University IRT Lab CUCS Site Visit January 2003

Overview What is ubiquitous computing? What is SIP? Location-based computing in SIP On-going work

Ubiquitous/pervasive computing Computers embedded into the environment Mobility, but not just cell phones Computation and communications Integration of devices “borrow” capabilities found in the environment  composition into logical devices seamless mobility  session mobility adaptation to local capabilities environment senses instead of explicit user interaction from small dumb devices to PCs

What are the core problems? Interested in multimedia communications (  Jason Nieh for computational mobility) Moving and splitting sessions Locating services Event notification

What is SIP? Session Initiation Protocol  protocol that establishes, manages (multimedia) sessions also used for IM, presence & event notification Developed at Columbia (with others) Standardized by IETF, 3GPP (for 3G wireless), PacketCable About 60 companies produce SIP products Microsoft’s Windows Messenger (4.7) includes SIP

Session mobility Walk into office, switch from cell phone to desk phone e.g., wall display + desk phone + PC for collaborative application SIP third-party call control

How to find services? Two complementary developments: smaller devices carried on user instead of stationary devices devices that can be time-shared Need to discover services in local environment SLP (Service Location Protocol) allows querying for services “find all color displays with at least XGA resolution” CU SLP extensions for scalable, resilient discovery Need to discover services before getting to environment “is there a camera in the meeting room?” CU SLP extension: find remote DA via DNS SRV

Determining locations For many devices, can’t afford hardware to determine location Implementing BlueTooth- based location sensor networks CU 7DS project: offer local content + location Developing programmable active badges with IR and RF capabilities

Location-based services CPL-based ruleset “Alice has entered Room 700” Make this Alice’s phone “WNYC” SIP-based event notification SIP-based messaging

Location filtering language location-filtering language “within 30’ of campus” “EST” 40.8N, 73.9W in train  only IM communication filtering geo civil categorical properties

Columbia SIP servers (CINEMA) Internal Telephone Extn: 7040 SIP/PSTN Gateway Department PBX Web based configuration Web server Telephone switch SQL database sipd: Proxy, redirect, registrar server Extn: 7134 NetMeeting H.323 rtspd: media server sipum: Unified messaging Quicktime RTSP clients RTSP Extn: x Single machine SNMP (Network Management) sipconf: Conference server siph323: SIP-H.323 translator Local/long distance

Pushing context-sensitive data to users User with mobile device should get location information when entering city, campus or building flight and gate information maps and directions local weather forecast special advisories (“choose security checkpoint 2”) Often does not require knowing user but interface with (e.g.) calendar Example Columbia implementation (7DS): OBEX data exchange over BlueTooth PDA pushes current appointment or event name base station delivers directions and map

Conclusion SIP + auxiliary protocols supports many of the core requirements for ubiquitous computing and communications: mobility modalities: terminal, user, session, service service negotiation for devices with different capabilities automatic configuration and discovery event notification and triggered actions automatic actions: event filtering, CPL, LESS SIP offers a loosely-coupled approach Also need data push functionality